[Diagnosis and management of urinary tract dilatations detected in utero]

About 1% of the newborns show abnormalities of the urinary tract, representing 25% of the antenatally detected malformations. Most of these urinary abnormalities are detected by prenatal ultrasound between the 14th and the 22nd week of gestation. Their outcome is determined during the first weeks of pregnancy and depends on the degree of renal impairment and the presence of associated extrarenal malformations. Establishing the outcome is often difficult, however it can be predicted by ultrasound and biochemistry of fetal urine. Prenatal management should consist in follow-up and careful organisation of the postnatal management of congenital uropathies. Every antenatally dilated urinary tract requires postnatal investigation. Postnatal ultrasound on the 3rd to 4th day of life is recommended for confirming or excluding urinary abnormalities. In case of persistence, ultrasound has to be completed by other radiologic methods. Voiding cystourethrography and/or nuclear renography allow to identify the origin of the observed abnormalities. Apart from a few situations needing immediate correction, surgical treatment is rarely indicated. The principal of postnatal management is prevention of urinary tract infections by antibiotic prophylaxis and a close follow-up until adulthood.